Question

The aerodynamic forces produced by a golf ball (lift and/or drag) depend on its diameter d, its speed V, its angular velocity w, and its dimple height h, as well as the air density p and viscosity . (a) You wish to define a force coefficient (a dimensionless force). Find an variables by which you can divide the force to make a dimensionless force coefficient. Show your work. appropriate combination of the above (b) Show that the appropriate dimensionless force coefficient is functionally dependent on the "reduced" angular frequency (wd/V), the dimple height ratio (h/d) and the Reynolds number. Show and explain all work. (Hint: you may want to choose p, V, and d as scaling (repeating) variables.) (c) Until 1990, there were two standard sizes for golf balls. The USGA ball was while the "British ball" was 41.1 mm in diameter. Assume that a golfer reduced frequency and Reynolds number are the same for each case (this may be a stretch, but assume it anyway). Also assume that the dimple height ratio is the same for each ball. If the (initial) drag on the USGA ball is 1.72 N for typical conditions, what would be the drag on the British ball under the same conditions? Which do you think would fly further under equivalent initial conditions? (and still is) 42.7 mm in diameter, can hit both balls such that the initial

Answer 1

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